Persistence of Synthetic Organic Chemicals
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Persistence of Synthetic Organic Chemicals
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Dioxin
PCB
DDT
10 µg/L
0.2 µg/L
< 0.1 µg/L
Organochlorines: persistence related to water solubility
Soluble in organic solvents, lipid tissues, organic sediments
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Bioaccumulation in Organisms
The chemical essentially dissolves into the lipid tissues
carbon
Dioxin
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Seawater
Arctic cod muscle
Narwhal blubber
14 - 46 ppb
0.0003 ppb
2440 - 9160 ppb
Toxaphene
50,000 X
~ 8 M X
carbon lipid400,000 tons: 1946 to 1974
(670 chemicals)
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Water
Organic Sediments
Environmental Persistence
Solubility of < 0.1 μg/L
Organic chemicals become stored in organic sediments
This protects them from degradation and increases their lifetime in the environment
DDT
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Lake Michigan
µg PCB/Kg sediment (parts per billion)
EPA 2004
mg Carbon /g sediment
N Concentration
Organic Carbon
PCBs
PCBs
“banned” in 1979
Open water PCB concentration = < 1 part per trillion
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Florida Lakes and Organics
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DDT
dichloro-diphenyl-trichloroethane
First Modern Pesticide
Insecticide developed to combat insect-borne disease
Use was later expanded to include agriculture
1948 Nobel Prize in Physiology and Medicine
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Launch of the Environmental Movement
1962human volunteers ingested 35 mg of DDT
primates were fed 33,000 times more DDT than the estimated exposure
Thinning egg shells
Lower hatching rates
Declining Eagle population
Carcinogenic
decline in the eagle population occurred before the DDT years (bounties between 1917 and 1942)
http://faculty.unionky.edu/rbotkin/RECM_480_ISSUE_16A_YES_BLUE.PPT#291,22,Issue%2016:%20Yes
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DDT levels ranging from 2,200 to 110,000 µg/kg (ppb) in organic soils and sediments.
Rita Island, Okeechobee
Organic soils
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Historically characterized by clear water and a highly prized sports fishery, it served as a popular destination for boaters, swimmers, and fishermen for decades.
Lake Apopka
30,800 acres
mean depth is 5.4 feet
15 miles northwest of Orlando
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AgricultureAgriculture
Pesticide Use in Agricultural Area
Pesticide use included high amounts of DDT
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"Lake Apopka is a big chemical soup," Michael Fry, a researcher from the University of California
Tower Chemical Company
Produced dicofol, a mixture of the pesticide DDT and DDE, a by-product of DDT. Periodic spills occurred there, but a particularly large accident in 1980 caused dicofol to spread into the lake
TOC content ranges from 33 to 37%
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In the 1970s, scientists considered Lake Apopka a prime place to harvest eggs and hatchlings to studythem in captivity.
In 1980 and 1981, scientists counted populations of 1,200 to 2,000 alligators in a single night on the lake
By the late 1980s, they counted only 150 per night
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Alligator Population crash was linked to poor egg viability
Alligators typically produce 40-45 eggs with a hatching rate of about 65%. In Lake Apopka, only 15-20% hatch
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Apopka's juvenile alligators have abnormal testes and ovaries and abnormal hormone balances
DDE, a breakdown product of DDT, is a major contaminant in Lake Apopka
DDE is known to block the action of testosterone
Estradiol Testosterone
Apopka males had high levels of estradiol relative to testosterone
DDT, DDE and Feminization of Alligators
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' Teeny Weenies '
Alligators in Florida's Lake Apopka have Smaller Penises
Kyla Dunne for PBS June, 1998
http://www.mindfully.org/Pesticide/Alligators-Apopka-PBS2jun98.htm
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Extra Credit
1. Bioaccumulation of synthetic organics is due to the fact that the chemicals dissolve into ______ tissues in organisms.
2. The first modern pesticide was __________________3.The lake north of Orlando contaminated with DDT4. Animals affected by DDT contamination in the lake indicated above.
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Assessing the Danger: Octanol
Synthetic Organics, Organochlorines
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SolubilityHexane
Acetone
Lipids
Carbon-based compoundsdissolve more easily in carbon-based solvents.
organochlorine carbon
carbon
carbon
Dioxin
OrganicSedimentscarbon
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How strong is the interaction?
BioaccumulationPersistence
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An Important Organic Solvent:Octanol
C8H18O
Octanol is used as a reference organic solvent for neutral organic chemicals
cc c
c cc c
c
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Octanol and Water
Octanol and water are immiscible (they do not mix)
Octanol is less dense than water: 0.824 g/cm3
octanol
water
C8H18O
C8H18O
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Octanol (Carbon/Hydrogen)
water
Carbon/hydrogen
Partitioning Between Octanol and Water
C10H20
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Octanol-Water Partitioning Coefficient
Kow = Concentration of chemical in octanolConcentration of chemical in water
At equilibrium
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water
1 L Octanol1L Water
Add 10 mg chemical
separate
chemical
chemical
Analyze the water phase for the chemical.Difference between initial amount and amount in water = amount in octanolThe ratio between the two yields the Kow
octanol
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Add 10 mg chemical
separate
ChemicalIn octanol
ChemicalIn water
0.01 mg L
9.99 mg L
Water phase octanol phase
Kow = 9.99 mg L
0.01 mg L
= 999
1 L Octanol1L Waterl
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Kow of some Organochlorine Compounds
DDT 8,000,000
PCBs 2,000,000 +
Dieldrin 1,600,000
Mirex 3,000,000
A high Kow indicates strong interaction withorganic solvents and, therefore, sediments and lipid tissues
chemical in octanolchemical in water
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Range for Some Modern Pesticides
Kow = 2 – 10,000 mL/g
Dicamba = 4Malathion = 2919Chlorpyrophos = 10,521
Far less potential for bioaccumulationRapid Breakdown (1/2 life measured in days)
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Simple Filtration
Carbon(most common component)
Ion Removal
Water Filters
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These filters, by nature, are quite small and because filter effectiveness is dependent on contact time of the water with the filter media, a larger, high-quality solid carbon block filter will be more effective at reducing contaminants at the same flow rate.
A high-quality solid block activated carbon replacement filter will filter water for between 7 and 10 cents per gallon. 2 gallons of filtered water per day would cost between $50 and $100 per year
Most Common Filtration
Solid Carbon Block faucet mount filters
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Activated CarbonActivated Carbon
Activation by heating
Extremely porous with high surface area: 500 m2/g
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Activated CarbonActivated Carbon
Filtration
Particle size removal > 0.5 microns (bacteria, fungi)
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Activated CarbonActivated Carbon
Absorption: spontaneous movement of primarily organic contaminants from water to carbon matrix.
Pesticides, volatile organicsCarbon matrix
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2,4-D2.4.5-TP (Silvex)AlachlorAtrazineCarbofuranChlordaneEndrinHeptachlor EpoxideLindaneMethoxychlorSimazineToxapheneBenzeneCarbon TetrachlorideChlorobenzene
EthylbenzeneMonochlorobenzeneMTBEO-DichlorobenzeneP-DichlorobenzeneStyreneTetrachloroetheneTolueneTrichloroetheneVOCs
AntidepressantsSteroids/Hormones Prednisone Prednisolone Progesterone Testosterone Cortisol/HydrocortisoneAntibiotics
Carbon Filter Removal